One thing to keep in mind is medicine has a bias towards no action unless the action is provably better. I don’t mean that as a critique. In the case of probio

One thing to keep in mind is medicine has a bias towards no action unless the action is provably better. I don’t mean that as a critique. In the case of probiotics, there seem to be few to no downsides, but unclear or unrepeatable upsides. Therefore, many doctors simply chose not to use them. Overall, this is largely a good attitude. You don’t want medicine to take wild swings at new and fad-like treatments. However, there are often times when they respond far too slowly to information that could help treatment.